Unusual conversion of substituted-3-formylchromones to 3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones: a facile and efficient route to novel 1,2,4-dithiazoles

Substituted 3-formylchromones react with 2-phenyl-4-dimethylamino-1-thia-3-azabuta-1,3-diene (4) or thio-benzamide (7) by heating their toluene solution in a sealed tube to give novel substituted 3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones (6a-e) in high yields.     

Strategic Synthesis of Heptacoordinated FeIII Bifunctional Complexes for Efficient Water Electrolysis

In this research, highly efficient heterogeneous bifunctional (BF) electrocatalysts (ECs) have been strategically designed by Fe coordination (C_R) complexes, [Fe₂L₂(H₂O)₂Cl₂] (C1) and [Fe₂L₂(H₂O)₂(SO₄)].2(CH₄O) (C2) where the high seven C_R number synergistically modifies the electronic environment of the Fe centre for facilitation of H₂O electrolysis. The electronic status of Fe and its adjacent atomic sites have been further modified by the replacement of −Cl⁻ in C1 by −SO₄²⁻ in C2 . Interestingly, compared to C1 , the O−S−O bridged C2 reveals superior BF activity with extremely low overpotential (η) at 10 mA cm⁻² (140 mV_OER, 62 mV_HER) and small Tafel slope (120.9 mV dec⁻¹_OER, 45.8 mV dec⁻¹_HER). Additionally, C2 also facilitates a high-performance alkaline H₂O electrolyzer with cell voltage of 1.54 V at 10 mA cm⁻² and exhibits remarkable long-term stability. Thus, exploration of the intrinsic properties of metal–organic framework (MOF)-based ECs opens up a new approach to the rational design of a wide range of molecular catalysts.     

Synthesis and characterization of a smart contrast agent sensitive to calcium

A novel first-generation Ca2+ sensitive contrast agent, Gd-DOPTRA has been synthesized and characterized. The agent shows approximately 100% relaxivity enhancement upon addition of Ca2+. The agent is selective and sensitive to Ca2+ also in the presence of Mg2+ and Zn2+. The relaxivity studies carried out in physiological fluids prove the prospects of the agent for in vivo measurements.     

Catalyst-free one-pot synthesis of 2,4,5-tri- and 1,2,4,5-tetrasubstituted imidazoles

The present work emphasizes catalyst-free 2,4,5-tri- and 1,2,4,5-tetra substituted imidazole synthesis using diversified aldehydes with benzil, ammonium acetate, or amines. Ammonium acetate plays a vital role as a reactant catalyst by dissociating into acetic acid to afford imine and diamine formation to ascertain the 2,4,5-tri- and 1,2,4,5-tetra substituted imidazoles. The key advantages of the current approach are efficient, greener, eco-friendly, and facile, with moderate to excellent yield in shorter reaction time at the temperature of 80°C. Ethanol:water as a solvent makes the reaction process eco-friendly. Overall, the described approach offers a promising route for the efficient and sustainable synthesis of substituted imidazoles, which have a wide range of applications in various fields, including pharmaceuticals, agrochemicals, and materials science.     

Increased Availability of Tryptophan in 5-Methyltryptophan-Tolerant Shoots of Catharanthus roseus and Their Postharvest in vivo Elicitation Induces Enhanced Vindoline Production

Ten 5-methyltryprophan (5-MT)-resistant multiple shoot culture lines in three genotypes of Catharanthus roseus were selected in vitro. The variant shoot lines displayed a differential threshold tolerance limit against the analogue stress, ranged from 20 to 70?mg/l 5-MT in the medium. The lines tolerant to 40?mg/l 5-MT stress were most stable and fast proliferating. All the selected lines in the presence of 5-MT stress recorded increased level of tryptophan in their free amino acid pool. Highest tryptophan accumulation occurred in lines P40, P30, D40, and N40 (i.e., 296.5, 241.0, 200.6, and 202.0???g/g dry wt., respectively). A concomitant increase in the total alkaloid content (2.3?C3.8?% dry wt.) under the analogue stress was also noticed in these lines when compared to 1.0?C1.58?% dry wt. in the respective wild-type shoot maintained on a stress-free medium. The HPLC analysis of the alkaloid extracts of the 5-MT-tolerant lines grown under analogue stress also revealed vindoline as a major constituent with maximum accumulation in lines N40, N30, D30, D40, and P40 (0.046, 0.032, 0.034, and 0.022?% dry wt., respectively). The rooted shoots of 5-MT-tolerant lines were successfully acclimatized under glasshouse environment wherein they grew normally and set seeds. Flowering twigs or leaves excised from 1-year-old glasshouse-grown plants of 5-MT variant lines upon postharvest in vivo elicitation with 30?mg/l 5-MT or 5.0?mg/l tryptophan registered an eight-to-tenfold increment in their vindoline content within 24?C48?h.     

Neurotoxin (N-Oxalyl-L-α,β-Diamino Propionic Acid) Content in Different Plant Parts of Grass Pea (Lathyrus sativus L.) Spanning Seedling to Maturity Stage: Does It Increase over Time?

ODAP (N-oxalyl-L-2,3-diaminopropionic acid) is present in the seeds of grass pea. In this study, variation of total ODAP accumulation in leaves throughout the crop growth starting from 40 days after sowing to maturity, and the distribution pattern of ODAP in different plant parts including the seeds at the mature stage was analyzed. Five grass pea accessions were evaluated for two subsequent growing seasons in one location of ICARDA, Aleppo (Syria). The results found that the rate of accumulation of total ODAP varied during plant development. Increased rates of synthesis were noticed in young leaves of grass pea. The highest total ODAP content in leaves was noted in the early growth stage (40–50 days after sowing). Mean total ODAP content in leaves ranged from 0.17 to 0.96 percent during 2010–2011 and from 0.19 to 1.28 percent during 2011–2012. During maturity, the total ODAP content was lowest in the seeds than in leaves, stems, pod cover, seed coat, and cotyledons. The ranges of total ODAP content were 0.13 (seed)–0.34 (stem), 0.20 (seed)–1.01 (leaf), 0.22 (seed)–0.62 (leaf), 0.21 (seed)–0.66 (leaf), and 0.21 (seed)–0.78 (leaf) percent in B387, B222, B390, Bio-520, and B587 accessions, respectively, during maturity. The results indicated that the rate of accumulation and synthesis of total ODAP varied during the plant lifespan. The lowest total ODAP content of leaves was observed after 130 days of sowing. The lower total ODAP content after the early vegetative stage of grass pea plants makes them suitable as a feed.     

Modulation of Singlet-Triplet Gap in Atomically Precise Silver Cluster-Assembled Material

Silver cluster-based solids have garnered considerable attention owing to their tunable luminescence behavior. While surface modification has enabled the construction of stable silver clusters, controlling interactions among clusters at the molecular level has been challenging due to their tendency to aggregate. Judicious choice of stabilizing ligands becomes pivotal in crafting a desired assembly. However, detailed photophysical behavior as a function of their cluster packing remained unexplored. Here, we modulate the packing pattern of Ag₁₂ clusters by varying the nitrogen-based ligand. CAM-1 formed through coordination of the tritopic linker molecule and NC-1 with monodentate pyridine ligand; established via non-covalent interactions. Both the assemblies show ligand-to-metal-metal charge transfer (LMMCT) based cluster-centered emission band(s). Temperature-dependent photoluminescence spectra exhibit blue shifts at higher temperatures, which is attributed to the extent of the thermal reverse population of the S₁ state from the closely spaced T₁ state. The difference in the energy gap (ΔE_ST) dictated by their assemblies played a pivotal role in the way that Ag₁₂ cluster assembly in CAM-1 manifests a wider ΔE_ST and thus requires higher temperatures for reverse intersystem crossing (RISC) than assembly of NC-1. Such assembly-defined photoluminescence properties underscore the potential toolkit to design new cluster- assemblies with tailored optoelectronic properties.